Photodetectors, i.e. devices which detect light or other electromagnetic energy, are widely used for a variety of applications such as imaging, security systems, gas sensing and others. A photodetector sensitive to infrared light is known as an infrared (IR) photodetector. The most advanced modern semiconductor photodetctors are designed as hetero-structures of different semiconductors. Infrared photodetectors, which work in the range 3-10 microns, are often based on relatively narrow band gap semiconductors such as GaAs, InSb, AlAs and their solid solutions. The highest performing IR photodetectors are currently cooled to a low temperature up to cryogenic in order to decrease the internal detector noise. At ambient or higher temperatures the performance significantly degrades because the dark current of photodetectors based on narrow band gaps increases dramatically as a result of the charge carriers' thermal generation. This temperature-dependent behaviour is a significant limitation, which restrains considerably the application of IR photodetectors in low power, low cost devices where the provision of complex cooling equipment is not practical.
It is a primary object of the invention to provide a semiconductor hetero-structure for electromagnetic energy sensing with improved thermo stability.